1. Field of the Invention
The present invention relates to, for instance, a toll collection system which exchanges required information with an on-board equipment (OBE) carried on an incoming vehicle through a radio communication at a tollgate of a toll road, e.g., an expressway.
2. Description of the Related Art
On a toll expressway, a ticket is issued to a user on a vehicle coming into the entrance gate of a tollhouse from an entrance gate official and the ticket is turned over to an exit gate official of the tollhouse. The exit gate official calculates a toll based on data recorded on the ticket turned over and collects the toll from the user.
Data recorded on a ticket are an entrance gate identification (ID) code, a vehicle type, an entrance gate passing time and the like. Of these data, a vehicle type is automatically determined by a vehicle type discriminator which is provided at the entrance lane. Elements for determining a vehicle type are overall length, height and number of axles. The capital letter of a number plate of a vehicle that is detected by a video camera may be added.
A problem in such a present toll collection system is that each vehicle has to stop when getting and turning over a ticket thus, causing traffic congestion. The handling of the ticket itself is troublesome for a user and moreover, he has to open/close the window.
A system is considered which calculates and collects a toll without using a ticket by providing a radio communication controller at the entrance and exit gate of a tollhouse, providing on-board equipment (OBE) having a communication function on each vehicle and exchanging data with this OBE when passing through the entrance and exit gates. According to this system it is possible to collect a toll rapidly without requiring a tollhouse official to contact a user during the vehicle passing process and sharply reducing a vehicle passing process time. This will solve the traffic congestion problem.
Data transmitted to the OBE from the radio communication controller are an entrance gate ID code, a vehicle type, an entrance gate passing time and the like, the same as the data that would be recorded on a ticket.
As an example of a toll collection through radio communication as described above, a system has been disclosed in the Japanese Patent Disclosure (Kokai) No. 06-232820 (laid open to public inspection on Aug. 19, 1994).
However, in this radio communication system, an automatic ticket issuing machine (ATIM) is required to cope with an abnormality in the communication. In other words, if no response is sent from the on-board equipment in response to the data sent from the radio communication controller, the transmission is judged abnormal and a ticket is issued to a user. Data to be recorded on the ticket are an entrance gate ID code, a vehicle type, an entrance gate passing time and the like, the same as above. At an exit gate, an exit gate official gets the ticket from the user and calculates and collects a toll based on the data recorded on the ticket.
The entrance gate ID code and the entrance gate passing time are transmitted to the on-board equipment from the antenna at a tollgate immediately after the vehicle enters the entrance gate of the tollhouse and the result of this transmission will soon be known.
On the other hand, a vehicle type is automatically determined by a vehicle type discriminator provided at the entrance lane. The vehicle type is decided when the rear of the vehicle passes the vehicle type discriminator in order to detect a timing of completing the process for one vehicle, and data are finally transmitted to the on-board equipment via the antenna of the tollgate. Thereafter, the transmission result is known.
If the overall length of a vehicle is not long as in ordinary vehicles, even when data are transmitted to the on-board equipment from the antenna at the tollgate when a vehicle type is determined after the rear of the vehicle passes the vehicle type discriminator, there is sufficient time and distance until the vehicle arrives at the location of the ATIM after the result of data transmission is known. Therefore, if the transmission is abnormal, a user is able to pass through the tollgate smoothly while perceiving the necessity for getting a ticket in advance.
However, if a vehicle is long and large such as a full trailer (overall length 18m), semi-trailer (overall length 12 m) and large-sized bus (overall length 12 m), a vehicle type is finally determined when the front of a vehicle comes considerably close to the ticket issuing machine and data are transmitted to the on-board equipment from the antenna of the tollgate. Thus, there is not much time at all when the vehicle arrives at the location of the ticket issuing machine after the result of the data transmission is known.
Therefore, if the communication is abnormal, a user on a long and large-sized vehicle becomes aware of the necessity for getting a ticket immediately before or in front of the ATIM and has to stop the vehicle suddenly.
Further, in such a radio communication type toll collection system, electronic waves for radio communication are constantly sent to the vehicle from the antenna installed at the road side. Or, a method was adopted, wherein the transmission of radio waves to a vehicle begins when detecting the passage of the vehicle and the radio communication process terminated when the vehicle passed an no vehicle was present in a communication area.
However, in such a conventional radio communication process, the vehicle and preceding as well as succeeding vehicles run close together in particular, on a toll road where there is much traffic volume and congestion. Therefore, a phenomenon will be produced, wherein onboard vehicle units carried on preceding and succeeding vehicles and on-board equipment carried on the current vehicle are present in the same radio communication area. As a result, there is a problem such that the preceding and succeeding vehicles produce interference from the radio waves transmitted from the onboard vehicle units and the communication cannot be processed properly.